Mine does the same. I do know that temps do vary with broody hens because they get off the nests to eat and defecate for brief periods. And during the summer I have had broodies sit with their eggs shoved out all around them. When I was less experienced I would try to put them back thinking she had rejected those or that she had been negligent & I know better than she that they needed her warmth. She would roll them right back out from under her. She just knew they were getting too warm. She has never failed to hatch all that she was setting.

Mine does that too, especially after I turn them. I did have a friend tell me that as chicks develop they produce heat that can effect the temp. She was telling me that every time you turn them, the embryo shifts effecting the heat. My eggies are due to hatch Saturday, here's hoping!

I posted the same thing the other day. Just getting ready for the eggs that are in the mail.
If you look for a post that read hate my lg that was mine. I have put dish cloths on the viewing windows at night when the temp goes down. This seems to help. I have no trouble with the humidity.I can raise it up or down any time I want. (use the same temp. water as the bator temp.. During the day I pull a red plug that seems to help on the temp rise during the day.. This is the last batch of eggs in this bator. I will get another kind because I don't like to baby sit all day and night!

I found that you are better off letting it swing - it is probably your room temp that made it swing....Mine got up to 101.5 yesterday, but the house was also at 70*. It's usually between 60 and 65*. It drops to 98.6* when the room temp goes under 60*...

Best thing to do if it gets too cold it to throw a blanket over the whole thing!